U.S. patent number 11,433,692 [Application Number 16/836,981] was granted by the patent office on 2022-09-06 for detection sensor, detection device, conveying device, and image forming device.
This patent grant is currently assigned to FUJIFILM Business Innovation Corp.. The grantee listed for this patent is FUJIFILM BUSINESS INNOVATION CORP.. Invention is credited to Masaya Kumei, Akira Mihara, Kazuhiro Sakai.
United States Patent |
11,433,692 |
Mihara , et al. |
September 6, 2022 |
Detection sensor, detection device, conveying device, and image
forming device
Abstract
A detection sensor includes: a single light-emitting element
that radiates light onto a conveyed material; and multiple
light-receiving elements that receive interference light including
the light that is scattered at a surface of the conveyed material
and the light that is scattered inside the conveyed material.
Inventors: |
Mihara; Akira (Kanagawa,
JP), Sakai; Kazuhiro (Kanagawa, JP), Kumei;
Masaya (Kanagawa, JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
FUJIFILM BUSINESS INNOVATION CORP. |
Tokyo |
N/A |
JP |
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Assignee: |
FUJIFILM Business Innovation
Corp. (Tokyo, JP)
|
Family
ID: |
1000006542760 |
Appl.
No.: |
16/836,981 |
Filed: |
April 1, 2020 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20210039406 A1 |
Feb 11, 2021 |
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Foreign Application Priority Data
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Aug 9, 2019 [JP] |
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JP2019-148000 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B41J
13/0009 (20130101); G01P 3/36 (20130101); B65H
20/02 (20130101); B65H 2513/10 (20130101) |
Current International
Class: |
B41J
29/38 (20060101); B41J 13/00 (20060101); B65H
20/02 (20060101); G01P 3/36 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2012163370 |
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Aug 2012 |
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JP |
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2018-51765 |
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Apr 2018 |
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JP |
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Primary Examiner: Nguyen; Lam S
Attorney, Agent or Firm: Oliff PLC
Claims
What is claimed is:
1. A detection device comprising: a detection sensor comprising: a
single light-emitting element that radiates light onto a conveyed
material; and a plurality of light-receiving elements that receive
interference light including the light that is scattered at a
surface of the conveyed material and the light that is scattered
inside the conveyed material, wherein the detection device further
comprises a detection mechanism that acquires detection results of
the plurality of light-receiving elements of the detection sensor,
and performs averaging processing on the detection results to
detect a conveying speed of the conveyed material, and wherein, in
plan view, the plurality of light-receiving elements are arranged
such that the light-emitting element is located therebetween in a
conveyance direction of the conveyed material.
2. The detection device according to claim 1, wherein, in plan
view, the plurality of light-receiving elements are arranged in a
circumferential direction centered about the light-emitting
element.
3. The detection device according to claim 2, wherein, in plan
view, distances from centers of each of the plurality of
light-receiving elements to a center of the light-emitting element
are equal.
4. A conveying device comprising: a conveying unit that conveys the
conveyed material; and the detection device according to claim 1
that detects the conveying speed of the conveyed material that is
conveyed by the conveying unit.
5. An image forming device comprising: the conveying device
according to claim 4; a first forming unit that forms an image on
the conveyed material conveyed by the conveying unit; and a second
forming unit that forms an image on the conveyed material at a
timing that is corrected based on the conveying speed of the
conveyed material detected according to a detection result of the
detection sensor which is arranged upstream from the second forming
unit in a conveyance direction of the conveyed material.
6. The image forming device according to claim 5, wherein the first
forming unit forms an image on the conveyed material at a timing
that is generated based on the conveying speed of the conveyed
material detected according to a detection result of the detection
sensor which is arranged upstream from the first forming unit in
the conveyance direction of the conveyed material.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is based on and claims priority under 35 USC 119
from Japanese Patent Application No. 2019-148000 filed Aug. 9,
2019.
BACKGROUND
(i) Technical Field
The present disclosure relates to a detection sensor, a detection
device, a conveying device, and an image forming device.
(ii) Related Art
Japanese Unexamined Patent Application Publication No. 2018-051765
discloses a substrate processing device provided with: a conveying
mechanism that conveys a long strip-shaped base material in a
longitudinal direction along a conveyance path configured of
multiple rollers; a processing unit that processes the base
material in a processing position on the conveyance path; an
encoder that detects the rotation speed of a detection roller that
is one of the multiple rollers; and a controller that acquires a
detection signal from the encoder and controls the processing unit.
The controller has: a first speed acquisition unit that acquires a
first speed that is the conveying speed of the base material
indicated by the detection signal; a second speed acquisition unit
that acquires a second speed that is the conveying speed of the
base material on the conveyance path, separate from the first speed
acquisition unit; a slip determination unit that determines whether
or not a slip of the base material with respect to the detection
roller has occurred, by comparing the first speed and the second
speed; a third speed acquisition unit that, in a case where it is
determined that the slip has occurred, acquires a third speed by
correcting the first speed; and an operation command unit that
outputs an operation command to the processing unit on the basis of
the third speed.
SUMMARY
In a configuration in which the conveying speed of a conveyed
material is detected using a detection sensor provided with a
single light-emitting element that radiates light onto the conveyed
material and a single light-receiving element that receives light
scattered by the conveyed material, there are cases where detection
errors occur.
Aspects of non-limiting embodiments of the present disclosure
relate to reducing detection errors for the conveying speed of a
conveyed material compared to a configuration provided with a
single light-emitting element and a single light-receiving
element.
Aspects of certain non-limiting embodiments of the present
disclosure address the above advantages and/or other advantages not
described above. However, aspects of the non-limiting embodiments
are not required to address the advantages described above, and
aspects of the non-limiting embodiments of the present disclosure
may not address advantages described above.
According to an aspect of the present disclosure, there is provided
a detection sensor including: a single light-emitting element that
radiates light onto a conveyed material; and multiple
light-receiving elements that receive interference light including
the light that is scattered at a surface of the conveyed material
and the light that is scattered inside the conveyed material.
BRIEF DESCRIPTION OF THE DRAWINGS
An exemplary embodiment of the present disclosure will be described
in detail based on the following figures, wherein:
FIG. 1 is a schematic diagram depicting the configuration of an ink
jet recording device according to the present exemplary
embodiment;
FIG. 2 is a schematic diagram depicting the configuration of a
detection sensor according to the present exemplary embodiment;
FIG. 3 is a schematic diagram in which the detection sensor
according to the present exemplary embodiment is seen from
below;
FIG. 4 is a schematic diagram depicting a modified example in which
the detection sensor depicted in FIG. 3 is provided with three
light-receiving elements;
FIG. 5 is a schematic diagram depicting a modified example in which
the detection sensor depicted in FIG. 3 is provided with four
light-receiving elements;
FIG. 6 is a schematic diagram depicting a modified example in which
the detection sensor depicted in FIG. 3 is provided with eight
light-receiving elements;
FIG. 7 is a schematic diagram depicting a modified example in which
the distance from the centers of each of the eight light-receiving
elements to the center of a light-emitting element are equal, in
the detection sensor depicted in FIG. 6;
FIG. 8 is a graph depicting a spectral distribution for each
frequency per unit time; and
FIG. 9 is a block diagram depicting a specific configuration of a
detection unit according to the present exemplary embodiment.
DETAILED DESCRIPTION
Hereinafter, an example of an exemplary embodiment according to the
present disclosure will be described on the basis of the
drawings.
(Ink Jet Recording Device 10)
First, an ink jet recording device 10 will be described. FIG. 1 is
a schematic diagram depicting the configuration of the ink jet
recording device 10.
The ink jet recording device 10 depicted in FIG. 1 is an example of
an image forming device that forms an image on a recording medium.
Specifically, the ink jet recording device 10 is a device that
discharges ink droplets onto continuous paper P (an example of a
recording medium) to form an image on the continuous paper P, as
depicted in FIG. 1. In other words, it can also be said that the
ink jet recording device 10 is an example of a discharge device
that discharges droplets.
More specifically, the ink jet recording device 10 is provided with
a conveying device 12, an image forming mechanism 30, and a control
unit 16, as depicted in FIG. 1. Hereinafter, the specific
configuration of each unit (the conveying device 12, the image
forming mechanism 30, and the control unit 16) of the ink jet
recording device 10 will be described.
(Conveying Device 12)
The conveying device 12 depicted in FIG. 1 is a device that conveys
a recording medium serving as an example of a conveyed material.
Specifically, the conveying device 12 is a device that conveys
continuous paper P serving as an example of a recording medium.
More specifically, the conveying device 12 has a conveying
mechanism 20 and a detection device 60.
The continuous paper P to be conveyed is a long recording medium
that is long in the conveyance direction in which the continuous
paper P is conveyed. Specifically, the continuous paper P may also
be paper in which multiple pages are arranged in the conveyance
direction. It should be noted that an example of a conveyed
material and an example of a recording medium are not restricted to
the continuous paper P. For example, flat sheets of paper may be an
example of a conveyed material and an example of a recording
medium.
Hereinafter, the specific configuration of each unit (the conveying
mechanism 20 and the detection device 60) of the conveying device
12 will be described. It should be noted that the detection device
60 will be described after the image forming mechanism 30 for the
convenience of the description.
(Conveying Mechanism 20)
The conveying mechanism 20 is an example of a conveying unit that
conveys a conveyed material. Specifically, the conveying mechanism
20 is a mechanism that conveys the continuous paper P. More
specifically, the conveying mechanism 20 has a wind-out roller 22,
a wind-in roller 24, multiple winding rollers 26, and multiple
support rollers 27, as depicted in FIG. 1.
The wind-out roller 22 is a roller that winds out the continuous
paper P. The continuous paper P is wound around the wind-out roller
22 in advance. The wind-out roller 22 rotates and thereby winds out
the continuous paper P that is wound therearound.
The multiple winding rollers 26 are rollers over which the
continuous paper P is wound. Specifically, the continuous paper P
is wound over the multiple winding rollers 26 between the wind-out
roller 22 and the wind-in roller 24. The conveyance path of the
continuous paper P from the wind-out roller 22 to the wind-in
roller 24 is thereby determined. Each of the multiple support
rollers 27 is a roller that supports the continuous paper P below
each discharge head 32Y, 32M, 32C, and 32K described later in the
image forming mechanism 30.
The wind-in roller 24 is a roller that winds in the continuous
paper P. The wind-in roller 24 is rotationally driven by a driving
unit 28. Thus, when the wind-in roller 24 winds in the continuous
paper P, the wind-out roller 22 winds out the continuous paper P.
Also, when the continuous paper P is wound in by the wind-in roller
24, the continuous paper P is wound out by the wind-out roller 22
and is thereby conveyed. The multiple winding rollers 26 and the
multiple support rollers 27 rotate in accordance with the movement
of the continuous paper P that is conveyed. It should be noted
that, in the drawings, the conveyance direction of the continuous
paper P (may be referred to as the "paper conveyance direction"
hereinafter) is depicted by an arrow X, as appropriate.
It should be noted that the configuration of the conveying
mechanism 20 is not restricted to the aforementioned configuration.
For example, the configuration of the conveying mechanism 20 may be
a configuration that conveys the continuous paper P from a housing
unit in which the continuous paper P is housed in a folded state,
to a housing unit in which the continuous paper P is housed in such
a way as to be folded. Furthermore, the configuration of the
conveying mechanism 20 may be a configuration in which a pair of
conveying rollers or a conveying belt or the like is used as a
conveying member that conveys the continuous paper P.
(Image Forming Mechanism 30)
The image forming mechanism 30 depicted in FIG. 1 is a mechanism
that forms an image on a recording medium. Specifically, the image
forming mechanism 30 discharges ink droplets onto the continuous
paper P conveyed by the conveying mechanism 20 to form an image. In
other words, it can also be said that the image forming mechanism
30 is an example of a discharge device that discharges ink droplets
as droplets.
More specifically, the image forming mechanism 30 has the discharge
heads 32Y, 32M, 32C, and 32K (hereinafter, referred to as 32Y to
32K), as depicted in FIG. 1.
The discharge heads 32Y to 32K are heads that discharge ink
droplets. Specifically, the discharge heads 32Y to 32K discharge
ink droplets of the colors of yellow (Y), magenta (M), cyan (C),
and black (B) onto the continuous paper P to form an image on the
continuous paper P. More specifically, the discharge heads 32Y to
32K are configured as described hereinafter.
As depicted in FIG. 1, the discharge heads 32Y to 32K are arranged
in this order toward the upstream side of the paper conveyance
direction. The discharge heads 32Y to 32K are long in the width
direction of the continuous paper P (may be referred to as the
"paper width direction" hereinafter). It should be noted that the
paper width direction is a direction intersecting (specifically, a
direction orthogonal to) the paper conveyance direction, and is
depicted in the drawings by an arrow Y, as appropriate.
The discharge heads 32Y to 32K have nozzle surfaces 30S in which
nozzles 30N are formed. The nozzle surfaces 30S of the discharge
heads 32Y to 32K face downward and oppose the continuous paper P
conveyed by the conveying mechanism 20. The discharge heads 32Y to
32K discharge ink droplets from the nozzles 30N onto the continuous
paper P using a publicly-known method such as a thermal method or a
piezoelectric method.
Water-based ink and oil-based ink are examples of the ink used in
the discharge heads 32Y to 32K. Water-based ink includes, for
example, a solvent containing water as the principle component
thereof, a colorant (specifically, a pigment, a dye, or the like),
and other additives. Oil-based ink includes, for example, an
organic solvent, a colorant (specifically, a pigment, a dye, or the
like), and other additives.
Here, the discharge head 32K is an example of a first forming unit.
The discharge heads 32C, 32M, and 32Y are examples of second
forming units. The discharge heads 32C, 32M, and 32Y discharge ink
droplets onto the continuous paper P to form an image on the
continuous paper P, at a timing that is corrected based on the
conveying speed of the continuous paper P detected by the detection
device 60.
It should be noted that any one or two of the discharge heads 32C,
32M, and 32Y may be understood to be examples of the second forming
unit. Consequently, in the present exemplary embodiment, in a case
where the discharge head 32K is taken as an example of the first
forming unit, it is possible for at least one of the discharge
heads 32C, 32M, and 32Y to be used as an example of the second
forming unit.
(Detection Device 60)
The detection device 60 depicted in FIG. 1 is an example of a
detection device that detects the conveying speed of a conveyed
material, and specifically, is a device that detects the conveying
speed of the continuous paper P conveyed by the conveying mechanism
20. More specifically, the detection device 60 has detection
sensors 40, 41, 42, and 43 and a detection unit 62, as depicted in
FIG. 1.
Hereinafter, the specific configuration of each unit (the detection
sensors 40, 41, 42, and 43 and the detection unit 62) of the
detection device 60 will be described.
(Arrangement of Detection Sensors 40, 41, 42, and 43)
The detection sensors 40, 41, 42, and 43 depicted in FIG. 1 are
sensors that are used to detect the conveying speed of the
continuous paper P. The detection sensor 40 is arranged upstream
from the discharge head 32K in the paper conveyance direction.
Furthermore, the detection sensors 41, 42, and 43 are arranged
among the discharge heads 32Y to 32K in the paper conveyance
direction. In other words, the detection sensor 41 is arranged
downstream from the discharge head 32K and upstream from the
discharge head 32C in the paper conveyance direction. The detection
sensor 42 is arranged downstream from the discharge head 32C and
upstream from the discharge head 32M in the paper conveyance
direction. The detection sensor 43 is arranged downstream from the
discharge head 32M and upstream from the discharge head 32Y in the
paper conveyance direction.
There may be more than one of each of the detection sensors 40, 41,
42, and 43. The multiple detection sensors 40, 41, 42, and 43 are
arranged in the paper width direction, for example. It is thereby
possible to detect the conveying speed of multiple sections of the
continuous paper P in the paper width direction. It should be noted
that the multiple detection sensors 40, 41, 42, and 43 may be
arranged in the paper width direction.
(Configuration of Detection Sensors 40, 41, 42, and 43)
The detection sensors 40, 41, 42, and 43 have similar
configurations, and therefore the configuration of the detection
sensor 41 will be described hereinafter.
Specifically, the detection sensor 41 has a single light-emitting
element 46 and multiple light-receiving elements 48, as depicted in
FIG. 3.
The light-emitting element 46 is an example of a light-emitting
element that radiates light onto a conveyed material. Specifically,
as depicted in FIG. 2, the light-emitting element 46 is a
light-emitting element that radiates light L1 onto the continuous
paper P conveyed by the conveying mechanism 20 (see FIG. 1). More
specifically, the light-emitting element 46 is configured of a
semiconductor laser (LD: laser diode) that radiates laser light,
and more specifically, is configured of a vertical-cavity
surface-emitting laser (VCSEL). It should be noted that the
light-emitting element 46 is not restricted to a vertical-cavity
surface-emitting laser, and, for example, may be an edge-emitting
laser or the like.
The light-receiving elements 48 are examples of a light-receiving
element that receives interference light including light that is
scattered at the surface of a conveyed material and light that is
scattered inside the conveyed material. Specifically, as depicted
in FIG. 2, the light-receiving elements 48 detect, as a beat
signal, the beat of light produced by interference between light L2
that is scattered at the surface of the continuous paper P conveyed
by the conveying mechanism 20 (see FIG. 1) and light L3 that is
scattered inside the continuous paper P. More specifically, the
light-receiving elements 48 are configured of photodiodes (PD). It
should be noted that the frequency of the light L2 scattered at the
surface of the continuous paper P and the frequency of the light L3
scattered inside the continuous paper P produce a Doppler shift
that corresponds to the conveying speed of the continuous paper P,
and therefore the beat signal also changes according to the
conveying speed of the continuous paper P.
In the present exemplary embodiment, the detection sensor 41 has
two light-receiving elements 48A and 48B as the multiple
light-receiving elements 48, as depicted in FIG. 3. Each of the
light-receiving elements 48A and 48B detects a beat signal.
(Arrangement of Light-Receiving Elements 48)
In plan view, the two light-receiving elements 48A and 48B are
arranged such that the light-emitting element 46 is located
therebetween, as depicted in FIG. 3. Specifically, in plan view,
the two light-receiving elements 48A and 48B are arranged such that
the light-emitting element 46 is located therebetween in the paper
conveyance direction X. More specifically, the light-receiving
element 48A is arranged upstream from the light-emitting element 46
in the paper conveyance direction, and the light-receiving element
48B is arranged downstream from the light-emitting element 46 in
the paper conveyance direction. It should be noted that plan view
refers to viewing in the vertical direction. FIGS. 3 to 7 depict
the case where the detection sensor 41 is seen from the continuous
paper P side (from below).
It can also be said that, in plan view, the two light-receiving
elements 48A and 48B are arranged in a circumferential direction
with the light-emitting element 46 as the center 46S. A
configuration of being arranged in the circumferential direction
with the light-emitting element 46 as the center 46S refers to a
configuration in which at least some of the light-receiving
elements 48 are arranged on a line 46L in the circumferential
direction with the light-emitting element 46 as the center 46S. In
addition, in plan view, the distances from the centers 48S of each
of the two light-receiving elements 48A and 48B to the center 46S
of the light-emitting element 46 are equal.
It should be noted that the detection sensor 41 may be a
configuration having three light-receiving elements 48A, 48B, and
48C as the multiple light-receiving elements 48, as depicted in
FIG. 4. In the configuration depicted in FIG. 4, in addition to the
light-receiving elements 48A and 48B depicted in FIG. 3, a
light-receiving element 48C is arranged at one side of the
light-emitting element 46 in the paper width direction Y.
Consequently, the light-receiving element 48C is arranged
downstream from the light-receiving element 48A in the paper
conveyance direction, and upstream from the light-receiving element
48B in the paper conveyance direction.
It can also be said that, in plan view, the three light-receiving
elements 48A, 48B, and 48C are arranged in a circumferential
direction with the light-emitting element 46 as the center 46S. In
addition, in plan view, the distances from the centers 48S of each
of the three light-receiving elements 48A, 48B, and 48C to the
center 46S of the light-emitting element 46 are equal.
It should be noted that the detection sensor 41 may be a
configuration having four light-receiving elements 48A, 48B, 48C,
and 48D as the multiple light-receiving elements 48, as depicted in
FIG. 5. In the configuration depicted in FIG. 5, in addition to the
light-receiving elements 48A, 48B, and 48C depicted in FIG. 4, a
light-receiving element 48D is arranged at the other side of the
light-emitting element 46 in the paper width direction. In other
words, the light-receiving element 48D is arranged downstream from
the light-receiving element 48A in the paper conveyance direction,
and upstream from the light-receiving element 48B in the paper
conveyance direction.
In addition, it can also be said that, in plan view, the
light-receiving elements 48C and 48D are arranged such that the
light-emitting element 46 is located therebetween. Specifically, in
plan view, the light-receiving elements 48C and 48D are arranged
such that the light-emitting element 46 is located therebetween in
the paper width direction Y.
Furthermore, it can also be said that, in plan view, the four
light-receiving elements 48A, 48B, 48C, and 48D are arranged in a
circumferential direction with the light-emitting element 46 as the
center 46S. In addition, in plan view, the distances from the
centers 48S of each of the four light-receiving elements 48A, 48B,
48C, and 48D to the center 46S of the light-emitting element 46 are
equal.
Furthermore, the detection sensor 41 may be a configuration having
eight light-receiving elements 48A, 48B, 48C, 48D, 48E, 48F, 48G,
and 48H as the multiple light-receiving elements 48, as depicted in
FIG. 6. In the configuration depicted in FIG. 6, in addition to the
light-receiving elements 48A, 48B, 48C, and 48D depicted in FIG. 5,
in plan view, light-receiving elements 48E and 48F are arranged
such that the light-receiving element 48A is located therebetween
in the paper width direction Y, and, in plan view, light-receiving
elements 48G and 48H are arranged such that the light-receiving
element 48B is located therebetween in the paper width direction
Y.
In the detection sensor 41, it can also be said that, in plan view,
the light-receiving elements 48E and 48G are arranged such that the
light-receiving element 48C is located therebetween in the paper
conveyance direction X, and, in plan view, the light-receiving
elements 48F and 48H are arranged such that the light-receiving
element 48D is located therebetween in the paper conveyance
direction X.
In addition, in the detection sensor 41, it can also be said that,
in plan view, the light-receiving elements 48E and 48H are arranged
such that the light-emitting element 46 is located therebetween in
a direction that is oblique with respect to the paper conveyance
direction X and the paper width direction Y. In addition, in the
detection sensor 41, it can also be said that, in plan view, the
light-receiving elements 48F and 48G are arranged such that the
light-emitting element 46 is located therebetween in a direction
that is oblique with respect to the paper conveyance direction X
and the paper width direction Y. It can also be said that, in plan
view, the eight light-receiving elements 48A, 48B, 48C, 48D, 48E,
48F, 48G, and 48H are arranged in a circumferential direction with
the light-emitting element 46 as the center 46S.
In the configuration depicted in FIG. 6, in plan view, the
distances from the centers 48S of each of the four light-receiving
elements 48A, 48B, 48C, and 48D to the center 46S of the
light-emitting element 46 are equal. Furthermore, in plan view, the
distances from the centers 48S of each of the four light-receiving
elements 48E, 48F, 48G, and 48H to the center 46S of the
light-emitting element 46 are equal. It should be noted that the
distances from the centers 48S of each of the four light-receiving
elements 48E, 48F, 48G, and 48H to the center 46S of the
light-emitting element 46 are longer than the distances from the
centers 48S of each of the four light-receiving elements 48A, 48B,
48C, and 48D to the center 46S of the light-emitting element
46.
The multiple light-receiving elements 48 may be a configuration
having the eight light-receiving elements 48A, 48B, 48C, 48D, 48E,
48F, 48G, and 48H, in which, in addition, the distances from the
centers 48S of each of the eight light-receiving elements 48A, 48B,
48C, 48D, 48E, 48F, 48G, and 48H to the center 46S of the
light-emitting element 46 are equal, as depicted in FIG. 7.
(Detection Method of Detection Unit 62)
The detection unit 62 is an example of a detection mechanism that
detects the conveying speed of a conveyed material. Specifically,
the detection unit 62 acquires detection results of the multiple
light-receiving elements 48 of the detection sensor 41, and detects
the conveying speed of the continuous paper P.
Here, a method for detecting the conveying speed of the continuous
paper P in the detection unit 62 will be described.
The detection unit 62 acquires beat signals detected by each of the
multiple light-receiving elements 48. Specifically, in the
detection unit 62, signal data of the beat signals detected by each
of the multiple light-receiving elements 48 is extracted using a
predetermined unit time range, and a fast Fourier transform (FFT),
for example, is executed on the data, thereby obtaining a spectral
distribution for each frequency .omega.. FIG. 8 depicts an example
of a graph 82 indicating the spectral distribution for each
frequency .omega. per unit time. It should be noted that the
horizontal axis of the graph 82 in FIG. 8 represents the frequency
.omega. and the vertical axis represents the spectral
intensity.
Here, the conveying speed is proportional to the average frequency
value of the power spectrum represented by the graph 82, and is
therefore proportional to a value obtained by dividing, by the area
of the hatched region 84, an integrated value obtained by
integrating the product of the frequency .omega. and the power
spectrum at the frequency .omega., with respect to the frequency
.omega.. In the detection unit 62, the integrated value is divided
by the area of the hatched region 84 to thereby calculate the
conveying speed.
(Specific Configuration of Detection Unit 62)
The detection unit 62, specifically, acquires detection results of
the multiple light-receiving elements of the detection sensor 41
and performs averaging processing on the detection results to
detect the conveying speed of the continuous paper P.
FIG. 9 depicts a block diagram depicting a specific configuration
of the detection unit 62. As depicted in FIG. 9, the detection unit
62 has a CPU (central processing unit: processor) 51, a ROM
(read-only memory) 52, a RAM (random-access memory) 53, a storage
54, an amplification circuit 66, and an A/D (analog/digital)
conversion circuit 68. The units of the detection unit 62 are
communicably connected to each other via a bus 59.
The CPU 51 is a central processing unit and executes various types
of programs and carries out data processing and so forth. More
specifically, the CPU 51 reads a program from the ROM 52 or the
storage 54 and executes the program with the RAM 53 as being used a
work area.
The ROM 52 stores various types of programs and various types of
data. The RAM 53 stores programs or data temporarily as a work
area. The storage 54 is configured of an HDD (hard disk drive) or
an SSD (solid state drive), and stores various types of programs
including an operating system and various types of data.
When the aforementioned programs are executed, the detection unit
62 executes various types of functions using the aforementioned
hardware resources. The functional configuration realized by the
detection unit 62 will be described.
As a functional configuration, the detection unit 62 has a
detection unit 72 and a processing unit 74, as depicted in FIG. 1.
Each functional configuration is realized by the CPU 51 reading and
executing a program stored in the ROM 52 or the storage 54.
The amplification circuit 66 amplifies voltages corresponding to
the intensity of light received by each of the multiple
light-receiving elements 48 to a voltage level specified as an
input voltage range for the A/D conversion circuit 68. It should be
noted that, as an example here, the light-receiving elements 48 are
elements that output voltages corresponding to the intensity of
received light; however, the light-receiving elements 48 may output
current corresponding to the intensity of received light, and in
this case, the amplification circuit 66 amplifies the current
output by the light-receiving elements 48 to a current level
specified as an input current range for the A/D conversion circuit
68.
The A/D conversion circuit 68 has input thereto the voltages
amplified by the amplification circuit 66, and converts the amounts
of light received by the light-receiving elements 48, represented
by the magnitude of the voltages, into numerical values and outputs
the numerical values.
The detection unit 72 has input thereto the amounts of received
light that have been converted into numerical values by the A/D
conversion circuit 68, carries out FFT processing on each amount of
light received by the light-receiving elements 48 to detect the
spectral distribution for each frequency .omega., and uses the
detected spectral distribution (see FIG. 8) to calculate a
conveying speed in accordance with the method already
described.
The processing unit 74 carries out averaging processing on the
conveying speed calculated for each light-receiving element 48, and
detects the conveying speed of the continuous paper P. In other
words, values for the conveying speed calculated for each
light-receiving element 48 are added and the result is then divided
by the number of light-receiving elements 48 to thereby obtain the
conveying speed of the continuous paper P.
It should be noted that in a configuration provided with three or
more light-receiving elements 48, averaging processing may be
carried out excluding values such as the largest value or the
smallest value with which the value of the conveying speed differs
considerably, for example.
(Control Unit 16)
The control unit 16 depicted in FIG. 1 is a control unit serving as
a control device that controls the operation of each unit of the
ink jet recording device 10.
Specifically, the control unit 16 has a storage unit configured of
a ROM, a storage, or the like in which programs are stored, and a
processor that operates according to the programs. The control unit
16 reads and executes the programs stored in the storage unit and
table information, and the operation of each unit of the ink jet
recording device 10 including the discharge heads 32Y to 32K is
thereby controlled.
The control unit 16 uses the conveying speed of the continuous
paper P detected according to the detection result of the detection
sensor 40 as a reference speed, and causes the discharge head 32K
to discharge ink droplets at a timing that is generated based on
this reference speed. In addition, the control unit 16 causes the
discharge head 32C to discharge ink droplets at a timing that is
corrected based on the conveying speed of the continuous paper P
detected according to the detection result of the detection sensor
41. Specifically, in the control unit 16, a correction time is
obtained according to the aforementioned reference speed, the
conveying speed detected according to the detection result of the
detection sensor 41, the discharge distance from the surface of the
continuous paper P to the discharge surface of the discharge head
32C, and the discharge speed of the ink droplets, for example, and
the discharge timing of the discharge head 32C is increased or
decreased by that correction time. Similarly, the control unit 16
causes the discharge head 32M to discharge ink droplets at a timing
that is corrected based on the conveying speed of the continuous
paper P detected according to the detection result of the detection
sensor 42, and causes the discharge head 32Y to discharge ink
droplets at a timing that is corrected based on the conveying speed
of the continuous paper P detected according to the detection
result of the detection sensor 43. It should be noted that the
control unit 16 and the detection unit 62 may be configured as a
common unit.
(Action and Effect of Present Exemplary Embodiment)
In the present exemplary embodiment, as previously mentioned,
specifically, the detection sensor 41 has a single light-emitting
element 46 and multiple light-receiving elements 48, as depicted in
FIG. 3. Also, detection results of each of the multiple
light-receiving elements 48 are acquired and averaging processing
is carried out on the detection results to detect the conveying
speed of the continuous paper P.
Therefore, detection errors for the conveying speed of the
continuous paper P are reduced compared to a configuration in which
the detection sensor 41 is provided with a single light-emitting
element 46 and a single light-receiving element 48. Thus,
fluctuations in the conveying speed of the conveying mechanism 20
are detected with a high degree of precision. As a result, image
defects are suppressed.
Here, in a configuration using multiple detection sensors provided
with a single light-emitting element and a single light-receiving
element (first configuration), due to assembly errors when
assembling multiple detection sensors that are separate components,
variation in the distance between the light-emitting element 46 of
each detection sensor and the continuous paper P and variation in
the distance between the light-receiving element 48 of each
detection sensor and the continuous paper P may occur.
In response, in the detection sensor 41 which is a single component
having a single light-emitting element 46 and multiple
light-receiving elements 48, since there is a single light-emitting
element 46 the problem of variation in the distance to the
continuous paper P does not occur, and also variation in the
distance between each light-receiving element 48 and the continuous
paper P is unlikely to occur compared to the first
configuration.
Furthermore, in the present exemplary embodiment, as previously
mentioned, the two light-receiving elements 48A and 48B are
arranged such that the light-emitting element 46 is located
therebetween in plan view, as depicted in FIG. 3.
Therefore, compared to a configuration in which one light-receiving
element 48 and q light-emitting element 46 are arranged such that
another light-receiving element 48 is located therebetween,
variation in the distance of each of the multiple light-receiving
elements 48 to the light-emitting element 46 decreases, and
variation in the amount of light received by the multiple
light-receiving elements 48 is suppressed.
Specifically, in the present exemplary embodiment, as previously
mentioned, in plan view, the two light-receiving elements 48A and
48B are arranged such that the light-emitting element 46 is located
therebetween in the paper conveyance direction X.
Thus, it is easy to reduce the dimension of the detection sensor 41
in the paper width direction Y compared to a configuration in which
the multiple light-receiving elements 48 are arranged such that the
light-emitting element 46 is located therebetween in the paper
width direction Y. As a result, it is easy for a highly dense
arrangement to be implemented when multiple detection sensors 41
are to be arranged in the paper width direction Y.
Furthermore, in the present exemplary embodiment, as previously
mentioned, in plan view, the two light-receiving elements 48A and
48B are arranged in a circumferential direction with the
light-emitting element 46 as the center 46S.
Therefore, compared to a configuration in which one light-receiving
element 48 and a light-emitting element 46 are arranged in a
circumferential direction with another light-receiving element 48
as the center, variation in the distance of each of the multiple
light-receiving elements 48 to the light-emitting element 46
decreases, and variation in the amount of light received by the
multiple light-receiving elements 48 is suppressed.
Furthermore, in the present exemplary embodiment, as previously
mentioned, in plan view, the distances from the centers 48S of each
of the two light-receiving elements 48A and 48B to the center 46S
of the light-emitting element 46 are equal.
Therefore, variation in the amount of light received by the
multiple light-receiving elements 48 is suppressed compared to a
configuration in which the distances from the centers of each of
the multiple light-receiving elements 48 to the center of the
light-emitting element 46 are different.
Furthermore, with a conventional laser Doppler velocimeter it is
necessary to focus the laser light using an optical system, but
with the detection sensor 41 of the present exemplary embodiment it
is not necessary to focus the laser light and the spot diameter of
the laser light can be kept large. Therefore, with the detection
sensor 41 of the present exemplary embodiment there is less
susceptibility to surface irregularities of the continuous paper P
(for example, embossed paper) and vibration in the paper thickness
direction.
Furthermore, with a conventional laser Doppler velocimeter,
although an optical system to separate and focus laser light is
necessary, with the detection sensor 41 of the present exemplary
embodiment, an optical system is not necessary and therefore the
sensor size is reduced. Therefore, the degree of arrangement
freedom is high with the detection sensor 41 of the present
exemplary embodiment.
Modified Examples
In the present exemplary embodiment, as previously mentioned, in
plan view, the two light-receiving elements 48A and 48B are
arranged such that the light-emitting element 46 is located
therebetween, as depicted in FIG. 3; however, the present
disclosure is not restricted thereto. For example, a configuration
may be adopted in which one light-receiving element 48 and a
light-emitting element 46 are arranged such that another
light-receiving element 48 is located therebetween.
Furthermore, in the present exemplary embodiment, as previously
mentioned, in plan view, the two light-receiving elements 48A and
48B are arranged in a circumferential direction with the
light-emitting element 46 as the center 46S; however, the present
disclosure is not restricted thereto. For example, a configuration
may be adopted in which one light-receiving element 48 and a
light-emitting element 46 are arranged in a circumferential
direction with another light-receiving element 48 as the
center.
Furthermore, in the present exemplary embodiment, as previously
mentioned in plan view, the distances from the centers 48S of each
of the two light-receiving elements 48A and 48B to the center 46S
of the light-emitting element 46 are equal; however, the present
disclosure is not restricted thereto. For example, a configuration
may be adopted in which the distances from the centers of multiple
light-receiving elements 48 to the center of a light-emitting
element 46 are different.
Furthermore, in the present exemplary embodiment, as previously
mentioned, the ink jet recording device 10 depicted in FIG. 1 is
used as an example of an image forming device; however, the present
disclosure is not restricted thereto. For example, an image forming
device of an electrophotographic system that forms images on a
recording medium using toner may serve as an example of an image
forming device. In this case, an example of a conveyed material may
be an intermediate transfer body onto which an image is transferred
from an image forming unit that forms the image, and which
transfers the image to a recording medium.
Furthermore, in the present exemplary embodiment, the control unit
16 uses the conveying speed of the continuous paper P detected
according to the detection result of the detection sensor 40 as a
reference speed, and causes the discharge head 32K to discharge ink
droplets at a timing that is generated based on this reference
speed; however, the present disclosure is not restricted thereto.
For example, a configuration may be adopted in which the conveying
speed of the continuous paper P is detected using an encoder
provided on a winding roller 26 arranged upstream of the discharge
head 32K in the paper conveyance direction, and the control unit 16
uses that conveying speed as a reference speed and causes the
discharge head 32K to discharge ink droplets at a timing that is
generated based on this reference speed. It should be noted that
the winding roller 26 on which the encoder is provided is taken as
a driving roller that conveys the continuous paper P, for
example.
The present disclosure is not restricted to the aforementioned
exemplary embodiment, and various modifications, alterations, and
improvements are possible without deviating from the gist of the
present disclosure. For example, two or more of the aforementioned
modified examples may be combined, as appropriate.
The foregoing description of the exemplary embodiments of the
present disclosure has been provided for the purposes of
illustration and description. It is not intended to be exhaustive
or to limit the disclosure to the precise forms disclosed. Many
modifications and variations will be apparent to practitioners
skilled in the art. The embodiment was chosen and described in
order to best explain the principles of the disclosure and its
practical applications, thereby enabling others skilled in the art
to understand the disclosure for various embodiments and with the
various modifications as are suited to the particular use
contemplated. It is intended that the scope of the disclosure be
defined by the following claims and their equivalents.
* * * * *